Immune checkpoint molecules that are directly associated with T cell exhaustion and have shown increased expression levels during chronic HIV infection include programmed cell death protein 1 (PD-1), cytotoxic T-lymphocyte antigen-4 (CTLA-4), T cell immunoglobulin and mucin domain-containing protein 3 (TIM-3), lymphocyte-activation gene 3 (LAG-3), and T cell immunoreceptor with immunoglobulin and ITIM domains (TIGIT). Here, PDCD1 is linked to HIV infectious disease.